JP6700822B2 - Microporous layer and fuel cell using the same - Google Patents

Description

  The present invention relates to a microporous layer containing a carbon material and a water repellent material, a gas diffusion layer, a membrane electrode assembly and a fuel cell.

  Membrane Electrode Assembly of a polymer electrolyte fuel cell has a gas diffusion electrode with an air electrode catalyst layer on one surface of the polymer electrolyte membrane and a gas with an anode catalyst layer on the opposite surface of the polymer electrolyte membrane. The diffusion electrode has a structure in which the solid polymer membrane and the catalyst layer are in contact with each other. Hereinafter, in the present specification, the membrane electrode assembly may be referred to as “MEA”.

  Polymer Electrolyte Fuel Cell (PEFC) sandwiches a membrane electrode assembly with a separator, supplies fuel to the anode and oxygen to the cathode, reacts the fuel and oxygen to generate water, and generates energy. It is a type of fuel cell that takes out electricity.

  The cathode gas diffusion layer is required to have good gas permeability and diffusivity in order to supply oxygen to the cathode catalyst layer. Further, it is necessary to have conductivity so that the electrons generated in the air electrode catalyst layer can be efficiently transported to the separator. Further, it is required to have a function of discharging generated water such as water repellency.

  There is an oxygen gain in the evaluation of these fuel cells. The oxygen gain is the difference between the current-potential curve (IV curve) when air is used and the IV curve when oxygen is used. In the case of air, the performance will be lower than that of oxygen, and it will be necessary to consider the structure and material, as it is affected by gas diffusivity and drainage. Therefore, the performance may vary depending on the usage.

  In an actual fuel cell, the oxygen utilization rate of air is about 50%. This means that 50% of the oxygen in the supplied air is consumed. Since the proportion of oxygen contained in air is 20%, it is assumed that when the utilization rate of air is 50%, the oxygen content is 10%, and that the oxygen concentration is lower near the catalyst. Therefore, attempts have been made to supply oxygen to the catalyst layer more efficiently.

  Patent Document 3 proposes a system in which an oxygen separation device is incorporated in a fuel cell. The oxygen separation device can surely increase oxygen, but the addition of equipment to the fuel cell increases cost and mass/volume.

Patent Document 4 proposes a fuel cell in which a cathode electrode is provided with oxygen-adsorbing carbon as an oxygen separating means for selectively separating oxygen from air. However, it is known that a carbon material having a large surface area (for example, a BET specific surface area of 500 to 1000 cm ² /g) adsorbs oxygen and has already been used as a catalyst carrier of a fuel cell. That is, Patent Document 4 does not intend to obtain more oxygen enrichment than the current situation.

  Patent Document 5 discloses a fuel cell cathode having a catalyst layer composed of a catalyst-supporting carbon and a polymer electrolyte, in which tetraphenylporphyrinato-cobalt(II)-benzylimidazole is present in the catalyst layer. Is proposed. Since the porphyrin complex is present as an oxygen adsorbent in the vicinity of the conductor on which the catalyst is supported, the diffusion path of oxygen molecules to the catalyst surface is secured by the oxygen adsorbent located in the vicinity of the catalyst. It is described that it is possible to increase the concentration of the reaction gas in the vicinity of the reaction site in the inside of the inside. However, tetraphenylporphyrinato-cobalt(II)-benzylimidazole is expensive.

  On the other hand, cerium oxide is known as a metal oxide that can assume trivalent and tetravalent states in a steady state. There is ceria zirconia (hereinafter sometimes referred to as "CZ") that is solid-dissolved with zirconia so that more trivalent compounds can be stably obtained. CZ has a function of absorbing and releasing oxygen at a temperature of 300° C. or higher, and is used as a promoter of an automobile exhaust gas catalyst.

  Patent Document 1 discloses a microporous layer to which CZ having oxygen absorbing/releasing ability is added. However, the disclosed CZ has a temperature of 300° C. or higher at which the oxygen storage/release ability is exhibited as described above. This temperature is outside the operating temperature range of a polymer electrolyte fuel cell (generally about 70 to 100° C.).

  Further, Patent Document 2 discloses a microporous layer containing cerium oxide for the purpose of suppressing deterioration of the membrane electrode assembly by hydrogen peroxide. However, cerium oxide has a low ability to absorb and release oxygen, and its operating temperature is very high.

In Non-Patent Document 1, SnO ₂ or Bi ₂ O ₃ is selected as the third component to be solid-dissolved in CZ, and the oxygen release start temperature becomes low for the following reasons. SnO ₂ is a typical n-type semiconductor, and reduction of Sn ⁴⁺ to Sn ²⁺ easily occurs. When a part of Ce ⁴⁺ is replaced with Sn ⁴⁺ , the oxygen storage/release capacity is improved. Regarding Bi ₂ O ₃ , when Ce ⁴⁺ or Zr ^{4+ in} the crystal lattice is partially replaced with Bi ³⁺ having a small valence, oxide ions (O ^{2 -} ) is omitted and vacancies are always generated. Since O ²⁻ can move through the vacancies, diffusion from inside the crystal easily occurs.

Chinese Patent No. 10247960 JP 2012-038479 A Japanese Patent No. 4011203 JP, 2005-294107, A Japanese Patent No. 4311070

"Materials Integration" Vo1.26 No. 01, 2013, p. 20-25

  As described above, attempts have been made to efficiently supply oxygen to the catalyst layer to achieve high power generation performance, but the system is upsized, and oxygen is efficiently supplied under the operating conditions of the polymer electrolyte fuel cell. It was difficult to supply to the catalyst layer.

  Therefore, in view of the above problems, it is an object of the present invention to provide a polymer electrolyte fuel cell having high power generation performance by efficiently supplying oxygen to the catalyst layer in the operating temperature range of the polymer electrolyte fuel cell. And

That is, the present invention includes the following [1] to [11].
[1] A microporous layer containing a carbon material, a water repellent material, and a material having an oxygen storage/release capacity at 0 to 100°C.
[2] The microporous layer according to the above [1], wherein the material having an oxygen storage/release capacity is cerium zirconium oxide containing at least one element selected from tin, manganese, praseodymium and bismuth.
[3] The material having the oxygen storage/release capacity is supported on a substrate, and the substrate is one or a mixture of two or more selected from alumina, silica, silica-alumina, titania, zeolite, zirconia and magnesia. The microporous layer according to the item [1] or [2].
[4] The microporous layer according to any one of the above items [1] to [3], wherein the material having the oxygen storage/release capacity carries a transition metal element.
[5] The microporous layer according to any one of the above items [1] to [4], wherein the carbon material is carbon particles or carbon fibers.
[6] The microporous layer according to any one of items [1] to [5], wherein the water repellent material is a fluororesin.
[7] A gas diffusion layer in which the microporous layer according to the above [1] to [6] and a gas diffusion electrode substrate are laminated.
[8] The air electrode catalyst layer and the fuel electrode catalyst layer which are arranged via a solid polymer membrane, and the above-mentioned [1] to [6] which is arranged outside the air electrode catalyst layer. An air electrode gas diffusion layer having a microporous layer,
A membrane electrode assembly having a fuel electrode gas diffusion layer disposed outside a fuel electrode catalyst layer.
[9] An air electrode catalyst layer and a fuel electrode catalyst layer arranged via a solid polymer membrane, and an air electrode gas diffusion layer according to the above [7], which is arranged outside the air electrode catalyst layer, A membrane electrode assembly having a fuel electrode gas diffusion layer disposed outside a fuel electrode catalyst layer.
[10] A fuel cell including the membrane electrode assembly according to the above [8] or [9].
[11] The method for operating the fuel cell according to the above item [10], wherein the temperature of the microporous layer in the fuel cell is set to be equal to or higher than the oxygen storage/release temperature of a material having oxygen storage/release capacity. Method.

  By using the microporous layer of the present invention, a polymer electrolyte fuel cell having high power generation performance can be obtained.

3 is an XRD pattern of the material (1) manufactured in Example 1. 9 is an XRD pattern of the material (9) manufactured in Comparative Example 1. 9 is an XRD pattern of the material (10) manufactured in Comparative Example 2.

  The microporous layer of the present invention contains a carbon material, a water repellent material, and a material having an oxygen storage/release capacity at 0 to 100°C. The microporous layer is porous and has pores distributed in the order of micrometers.

[Materials that have the ability to store and release oxygen]
The material having an oxygen storage/release capacity used for the microporous layer has an oxygen release start temperature of 0 to 100°C.

Examples of the material having an oxygen storage/release capacity include metal oxides. Among them, cerium oxide (CeO ₂ ) and metal oxides containing cerium oxide, for example, cerium zirconium oxide (Ce _(1-x) Zr _X O ₂ ) Is well known. However, the oxygen release start temperature is 500° C. or higher.

  When elements such as tin (Sn), manganese (Mn), praseodymium (Pr), and bismuth (Bi) are added to the cerium-zirconium oxide, a metal oxide having an oxygen release starting temperature of 0 to 100° C. can be obtained. You can Among them, tin (Sn) and bismuth (Bi) are preferable because they have a lower oxygen release starting temperature.

For example, tin-containing cerium zirconium oxide is represented by the general formula Ce _(1-xy) Zr _x Sn _y O ₂ . In this composition, when the values of x and y are preferably in the ranges of 0.1≦x≦0.3 and 0.1≦y≦0.3, tin easily dissolves in cerium zirconium oxide. Therefore, a material having a large oxygen storage/release capacity and an oxygen release start temperature of 0 to 100° C. can be obtained.

Further, the bismuth-containing cerium zirconium oxide is represented by the general formula Ce _(1-xy) Zr _x Bi _y O ₂ . In this composition, preferably, when the values of x and y are in the ranges of 0.1≦x≦0.4 and 0.1≦y≦0.3, bismuth is likely to form a solid solution with cerium zirconium oxide. Therefore, a material having a large oxygen storage/release capacity and an oxygen release start temperature of 0 to 100° C. can be obtained.

Further, in order to enhance the oxygen storage capacity, the material having the oxygen storage/release capacity has a BET specific surface area of 40 m ² /
It is preferably at least g, and more preferably at least 70 m ² /g.

  Since the BET specific surface area can be increased and the oxygen storage capacity can be enhanced, the metal oxide, which is the material having the oxygen release initiation capacity, may be supported on the base material.

  The base material is not particularly limited, but a high specific surface area base material is usually used, and preferably alumina (active alumina is more preferred), silica (active silica is more preferred), silica alumina, titania, zeolite. , One or more selected from zirconia and magnesia, and mixtures thereof.

  Above all, it is particularly preferable to support the oxygen-releasing metal oxide on alumina or titania because the oxygen-releasing start temperature can be further lowered. The supported amount of the metal oxide having the above oxygen release starting temperature is preferably 1 to 9 parts by mass with respect to a total of 100 parts by mass of alumina or titania. It is more preferably 5 to 40 parts by mass.

  In order to further lower the oxygen release initiation temperature, a transition metal element may be further supported on the metal oxide having the oxygen releasing ability or the metal oxide supported on the base material. The transition metal element is not particularly limited, but a noble metal or a transition metal oxide can be used.

  Examples of the noble metal include platinum, palladium, silver and alloys thereof, of which platinum is preferred. The noble metal is preferably nanoparticles in terms of easiness of being carried, and more preferable when the particle size is 2 to 20 nm because the oxygen storage capacity also becomes high.

  The supported amount of the noble metal is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the base material. If the loading amount is 0.01 parts by mass or more, the oxygen release starting temperature can be easily lowered, and if the loading amount is 1 part by mass, the oxygen release starting temperature can be sufficiently lowered. Then, 5 parts by mass or less is preferable.

  Examples of the transition metal oxide include at least one selected from cobalt oxide, manganese oxide, chromium oxide, vanadium oxide, titanium oxide, tungsten oxide, copper oxide, nickel oxide, zinc oxide, silver oxide and cadmium oxide. Can be mentioned. The supported amount of the oxide catalyst is preferably 5 to 90 parts by mass, and more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the base material. Within the above range, the oxygen release start temperature can be easily lowered.

<Measuring method of oxygen storage/release capacity>
The oxygen storage/release capacity can be measured using a temperature rising desorption process measurement of a catalyst analyzer. For example, the sample is heated to 400° C. with atmospheric gas and then cooled to room temperature. Next, the temperature is raised to 400° C. with a reducing gas, and hydrogen is measured with a thermal conductivity detector (TCD) and a quadrupole mass spectrometer (MS). A substance whose hydrogen consumption is detected has an oxygen storage/release capacity. The temperature at which hydrogen consumption starts is determined as the oxygen release start temperature. The material having an oxygen storage/release capacity used in the present invention has an oxygen release start temperature in the range of 0 to 100°C.

<Method for producing material having oxygen storage/release capacity>
As a method for producing a material having an oxygen storage/release capacity used in the present invention, a method for producing tin-containing cerium zirconium oxide will be described below as an example, but the same production can be performed using raw materials of different metal elements.

  As a raw material for supplying each element of cerium, zirconium or tin, nitrate, oxynitrate, chloride, oxychloride, sulfate, oxysulfate, acetate, citrate, etc. of the above elements can be used. Examples include soluble compounds.

  A predetermined amount of the raw material is dissolved in water or an acidic aqueous solution, and alkali is added dropwise to obtain a precipitate. The alkali is preferably one that does not contain a metal element because it can be removed by firing. For example, ammonia is preferred. After the precipitate is repeatedly separated and washed with water, it is dried to obtain a precursor. The precursor is fired to produce tin-containing cerium zirconium oxide. Thereafter, the obtained tin-containing cerium zirconium oxide is preferably crushed using a mortar, a ball mill, a jet mill or the like to increase the specific surface area and used.

  Although the firing conditions of the precursor vary depending on the composition, it is preferable that the temperature is 300 to 600° C. and the firing time is 30 minutes to 10 hours. Within this range, tin is likely to form a solid solution with cerium zirconium oxide. There is no problem with the firing atmosphere even in the atmosphere. Baking in a reducing atmosphere is preferable because it can lower the oxygen release start temperature and increase the oxygen storage/release capacity. Although details are unknown, it is considered that the reduction-calcined product has a low ionization potential, which is somehow related to the mechanism of the oxygen storage/release capacity.

  The firing atmosphere gas may be hydrogen, but a mixed gas of nitrogen, argon or helium and hydrogen is preferable because it is easy to handle. The concentration of hydrogen gas is preferably 1 to 20% by volume, more preferably 1 to 5% by volume.

  Next, the method of supporting the material having the oxygen storage and release capacity on alumina or titania will be described by taking the method of supporting tin-containing cerium zirconium oxide on alumina as an example, but the application to the present invention is a combination of these. Not limited to

  A raw material for supplying a predetermined amount of each element of cerium, zirconium, and tin and alumina are added to water or an acidic aqueous solution, and then alkali is added dropwise to obtain a precipitate. Then, in the same manner as in the method for producing the tin-containing cerium zirconium oxide, the precipitate is repeatedly separated and washed with water, then dried to obtain a precursor, which is calcined, and the tin-containing cerium oxide supported on alumina is then obtained. Zirconium can be obtained.

  Next, a method for supporting a transition metal element (noble metal) on the material having oxygen storage/release capacity will be described by taking a method for supporting platinum on tin-containing cerium zirconium oxide as an example, but the application to the present invention is not limited to these. It is not limited to the combination.

  The tin-containing cerium zirconium oxide is dispersed in a platinum colloidal solution, the solvent is distilled off, and the solution is dried. Then, in order to decompose and remove the dispersant and the like contained in the colloid solution, baking is performed in the atmosphere. The firing conditions are preferably a temperature of 200 to 500° C. and a firing time of 10 minutes to 5 hours. Instead of the platinum colloid solution, chloroplatinic acid may be dissolved and subjected to reduction treatment.

  Next, a method for supporting a transition metal element (transition metal oxide) on the material having the oxygen storage/release capacity will be described by taking a manufacturing method for supporting tricobalt tetraoxide on tin-containing cerium zirconium oxide as an example. Application to the invention is not limited to these combinations.

  Cobalt nitrate is dissolved in water, the tin-containing cerium zirconium oxide is added, and the mixture is stirred. Then, the solvent is distilled off to obtain a precursor, which is fired. The firing conditions are preferably a temperature of 300 to 600° C. and a firing time of 30 minutes to 10 hours.

  The loading may be carried out a plurality of times, and different types of transition metal elements (for example, a noble metal and a transition metal oxide) may be loaded.

<Microporous layer>
The microporous layer of the present invention is a microporous layer containing the material having an oxygen storage/release capacity at 0 to 100° C. and further containing a carbon material and a water repellent material.

The microporous layer may be added with commonly used additives as needed. The gas diffusion performance of the microporous layer can be evaluated by measuring Gurley. Here, the Gurley is the air resistance measured by the method specified in Japanese Industrial Standard JISP8117.
Generally, when the Gurley is low, the oxygen supply from the separator side to the catalyst layer side is poor and the power generation efficiency is low. High Gurley is preferable, but a microporous layer having a high Gurley is liable to be cracked and has low strength. Therefore, the Gurley of the microporous layer of the present invention is preferably 5 to 40 seconds, more preferably 10 to 30 seconds, still more preferably 15 to 25 seconds.

  The higher the conductivity of the microporous layer of the present invention is, the more preferable it is, 50 S/cm or more is preferable, and 80 S/cm or more is more preferable.

  Generally, liquid water is present in a polymer electrolyte fuel cell, and therefore the operating temperature of the fuel cell is between the freezing point of water and the boiling point (0 to 100° C.). Therefore, in the present invention, a material having an oxygen storage/release ability at 0 to 100° C. is used as the material having the oxygen storage/release ability.

  A material having an oxygen storage/release capacity at 0 to 100° C. stores oxygen on the separator side having a high oxygen concentration, propagates oxygen in the microporous layer, and releases oxygen on the catalyst layer side having a low oxygen concentration. Therefore, the supply to the catalyst layer is increased and the power generation efficiency can be improved.

  Further, since the material having the oxygen storage/release capacity is hydrophilic, the inside of the microporous layer can be moistened. Therefore, by adding an appropriate amount, it is possible to enhance the power generation efficiency in low-humidification and even in non-humidified cathode dust.

  The content of the oxygen storage/release material in the microporous layer is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and further preferably 20 to 40% by mass. Within the above range, the oxygen release starting temperature can be easily lowered, and the strength and Gurley of the microporous layer can be easily maintained appropriately.

<Carbon material>
The carbon material used in the present invention is not particularly limited, and at least one kind or mixture of conductive carbon particles, carbon particles such as amorphous carbon, graphite, and graphene, conductive carbon fibers, and carbon fibers such as carbon nanotubes can be used.

  For example, as the conductive carbon particles, it is usually preferable to use particles having an average particle size of 5 nm to 200 nm. Channel black, furnace black (for example, Vulcan XC72 manufactured by CABOT), Ketjen black (for example, Ketjen Black EC manufactured by Lion Co., Ltd.), acetylene black (for example, Denka black manufactured by Denki Kagaku Co., Ltd.), Ranka black, etc. Carbon black, etc.

  The conductive carbon particles can increase the conductivity of the microporous layer. 0.1-20 mass% is preferable, as for content of the electroconductive carbon particle in a microporous layer, 1-10 mass% is more preferable, 2-7 mass% is further more preferable. Within this range, it is easy to keep the Gurley moderately.

  The graphite is not particularly limited, but natural graphite, artificial graphite or the like can be used. Natural graphite is divided into scaly graphite, scaly graphite and earthy graphite. As artificial graphite, crushed artificial graphite electrodes, petroleum-based heavy oil, coal-based heavy oil, petroleum-based coke, coal-based coke, pitch-based carbon fiber in a non-oxidizing atmosphere at 1500 to 3200° C. Included are mesophase microspheres.

  Such graphite can increase the conductivity of the microporous layer, form voids, and improve the gas diffusivity. The content of graphite in the microporous layer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and even more preferably 15 to 50% by mass. Within this range, it is easy to keep the strength of the microporous layer moderate.

  As the conductive carbon fiber, it is preferable to use one having a fiber diameter and a fiber length that facilitate dispersion. The average fiber diameter is preferably 20 to 500 nm, more preferably 100 to 300 nm. The average fiber length is preferably 2 to 100 μm, more preferably 5 to 30 μm. For example, vapor grown carbon fiber may be used. These can be used alone or in combination of two or more.

  The conductive carbon fiber can increase the conductivity of the microporous layer and suppress the occurrence of cracks. 0-50 mass% is preferable, as for content of the electrically conductive carbon fiber in a microporous layer, 2-35 mass% is more preferable, and 5-20 mass% is further more preferable. Within this range, it is easy to keep the Gurley moderately.

<Water repellent material>
A fluororesin or the like is used as the water repellent material. The fluorine-based resin can be preferably used in the present invention as long as it is a polymer containing fluorine and having a weight average molecular weight of about 100,000 to 10,000,000. As the fluorine-based resin, known or commercially available products can be used. Examples thereof include polytetrafluoroethylene resin (PTFE), fluorinated ethylene propylene resin (FEP), perfluoroalkoxy resin (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE). These can be used alone or in combination of two or more.

  The content of the fluororesin in the microporous layer is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, and further preferably 10 to 40% by mass. Within this range, it is easy to keep the Gurley moderately.

  By containing the fluorine-based resin in this manner, high water repellency can be imparted to the microporous layer, and conductive carbon particles and the like can be firmly bound, so that excellent water repellency can be maintained for a long period of time. ..

<Method of manufacturing microporous layer>
The microporous layer of the present invention is formed, for example, by applying a microporous layer forming ink on a holding sheet to form a microporous layer. Then, it can be obtained by peeling the microporous layer from the holding sheet.

  Next, the ink for forming the microporous layer will be described. The ink for forming a microporous layer contains the material having an oxygen storage/release capacity at 0 to 100° C., the carbon material, the water repellent material, and a solvent. Further, in order to disperse those materials in a solvent, it is preferable that the ink contains a dispersant.

  The solvent is not particularly limited and, for example, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-butanol, ethylene glycol, propylene glycol and the like having 1 to 4 carbon atoms. Preferable examples thereof include about 1 to 3 valent alcohols. These solvents may be used alone or in combination of two or more. Water is preferable because it is easy to handle.

  As the dispersant, known or commercially available dispersants can be used. Examples of the aqueous dispersant include polyoxyethylene alkylene alkyl ether, polyethylene glycol alkyl ether, polyoxyethylene fatty acid ester, and acidic group-containing structure-modified polyacrylate. Specific examples of octylphenoxypolyethoxyethanol include Triton X-100 manufactured by ACROS ORGANICS.

  Even if the dispersibility is increased, the dispersibility is not improved, and when the dispersibility remains, the conductivity of the microporous layer is lowered. The amount of the dispersant added to the solvent is preferably 1 to 30 parts by mass with respect to a total of 100 parts by mass of the material having the oxygen storage/release capacity in the solvent, the carbon material, and the water repellent material. 3 to 20 parts by mass is more preferable, and 5 to 15 parts by mass is further preferable.

  The method for producing an ink for forming a microporous layer is, for example, a material having an oxygen storage/release ability, a carbon material, and a water repellent material are weighed so that a predetermined content of the microporous layer is obtained, and these materials are mixed with a dispersant. Is dispersed in a solvent in which is dissolved by using ultrasonic waves or the like.

  The method for applying the ink for forming the microporous layer is not particularly limited, and any known method can be used. For example, general methods such as knife coater, bar coater, blade coater, sprayer, dip coater, spin coater, roll coater, die coater, curtain coater, screen printing and the like can be applied.

  The drying may be air drying, or may be dried with a dryer, a vacuum dryer or the like. With air drying, it is dried overnight. In a dryer, it is usually performed in the air at 80 to 150°C. The drying time is appropriately determined according to the drying temperature and the like, and is usually 5 to 60 minutes. Then, the obtained dried product is fired.

  By this baking treatment, the surfactant is completely removed, and the fluororesin contained in the microporous layer is thermally fused. It imparts excellent water repellency and gas permeability to the microporous layer of the present invention.

  The calcination can be performed by a heat treatment using a tubular furnace, an upper lid furnace, a tunnel furnace, a box furnace, a truck furnace, or the like. The firing temperature is not particularly limited and is, for example, 150 to 450° C., preferably 200 to 300° C. in the atmosphere.

  The firing time is appropriately determined depending on the firing temperature, but is usually about 5 to 120 minutes, preferably 15 to 60 minutes.

<Gas diffusion layer>
The gas diffusion layer of the present invention comprises the microporous layer formed on one surface of a gas diffusion electrode substrate. Among them, it is preferable that carbon paper is used as the gas diffusion electrode base material and a microporous layer is attached to the carbon paper because it is inexpensive.

  The Gurley of the diffusion layer is preferably 5 to 40 seconds, more preferably 10 to 30 seconds, and even more preferably 15 to 25 seconds, like the microporous layer.

  The electric conductivity of the gas diffusion layer is preferably 50 S/cm or more, more preferably 80 S/cm or more, as in the case of the microporous layer.

Basis weight of Micropolar lath layer in the gas diffusion layer is preferably 0.5-20 / cm ^2, preferably from 1-10 mg / cm ^2, more preferably 1.5 to 5 mg / cm ^2.

  The gas diffusion electrode base material is not particularly limited as long as it has conductivity and is porous, and known or commercially available materials can be used. Examples thereof include carbon paper, carbon cloth, carbon non-woven fabric (carbon felt), and carbon woven fabric. Of these, carbon paper is preferable because it is inexpensive. The thickness of the carbon paper is usually 50 μm to 1000 μm, preferably 100 μm to 400 μm. For example, TGP-H series manufactured by Chemix Co., Ltd. may be mentioned.

  The gas diffusion electrode substrate is preferably subjected to water repellent treatment in advance in order to improve water repellency. As the water repellent treatment, for example, the conductive porous substrate is immersed in an aqueous dispersion such as polytetrafluoroethylene emulsion, and then dried and baked. The content of polytetrafluoroethylene in the emulsion is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass with respect to 100 parts by mass of water.

<Method for manufacturing gas diffusion layer>
The method for producing the gas diffusion layer of the present invention is not limited,
(I) A microporous layer forming ink is applied to the gas diffusion electrode substrate.
Or
(Ii)-1 A microporous layer forming ink is applied to a holding sheet to form a microporous layer.
(Ii)-2 The microporous layer is peeled off from the holding sheet.
(Ii)-3 The microporous layer is attached to the gas diffusion electrode substrate.
And the like.
Above all, the above (i) is preferable because it is simple and a stable gas diffusion electrode with less peeling and cracks between the microporous layer and the gas diffusion electrode base material can be manufactured. The gas diffusion electrode base material such as carbon paper may be previously subjected to water repellent treatment.

[Membrane electrode assembly]
The membrane electrode assembly of the present invention comprises a solid polymer membrane, an air electrode catalyst layer and a fuel electrode catalyst layer which are arranged so as to sandwich the solid polymer membrane, and an air electrode gas diffusion layer which is arranged outside the air electrode catalyst layer. And a fuel electrode gas diffusion layer disposed outside the fuel electrode catalyst layer, and the microporous layer or the gas diffusion layer is used as an air electrode gas diffusion layer.

  A publicly known or commercially available solid polymer film can be used. For example, those produced by applying a solution containing a hydrogen ion conductive polymer electrolyte onto a substrate and drying the solution are also included. Examples of the hydrogen ion conductive polymer electrolyte include a solid polymer membrane using a perfluorosulfonic acid polymer and a solid polymer membrane using a hydrocarbon polymer. Further, a membrane in which a polymer microporous membrane is impregnated with a liquid electrolyte or a membrane in which a porous body is filled with a polymer electrolyte may be used.

  The air electrode gas diffusion layer uses the microporous layer of the present invention or the gas diffusion layer of the present invention as the air electrode gas diffusion layer. As the fuel electrode gas diffusion layer, a known or commercially available gas diffusion layer can be used. The gas diffusion electrode substrate can be used as it is for the fuel electrode gas diffusion layer. Further, the microporous layer or the gas diffusion layer may be used as the fuel electrode gas diffusion layer.

Known or commercially available catalyst layers can be used for the air electrode catalyst layer and the fuel electrode catalyst layer. These catalyst layers generally contain a catalyst, a polymer electrolyte, and electron conductive particles. Moreover, you may contain the other additive as needed. Platinum is generally used as the air electrode catalyst. Platinum or a platinum alloy is generally used as the fuel electrode catalyst. The platinum alloy is composed of platinum and at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron and cobalt. Basis weight of the catalyst layer is preferably 0.01 to 1.0 mg / cm ^2, more preferably 0.02~0.7mg / cm ^2, more preferably 0.05 to 0.5 / cm ^2.

  The method for producing the membrane electrode assembly is not particularly limited, and it can be performed by a known method. For example, an air electrode catalyst layer and a fuel electrode catalyst layer are arranged so as to sandwich a solid polymer membrane, and an air electrode gas diffusion layer is arranged outside the air electrode catalyst layer so that the microporous layer is in contact with the catalyst layer. A fuel electrode gas diffusion layer is arranged outside the electrode catalyst layer. Then, it can be manufactured by performing a hot pressing process such as hot pressing.

[Polymer Fuel Cell]
The polymer electrolyte fuel cell of the present invention can be formed by providing the membrane electrode assembly with a known or commercially available separator.
The fuel to be supplied to the polymer electrolyte fuel cell is not particularly limited as long as it can generate protons at the anode, hydrogen, alcohols such as methanol, saccharides such as glucose, hydrogen, Alternatively, methanol is preferred. Water may be mixed in the fuel, and when the fuel is supplied as a gas, the water is preferably steam.

  Oxygen is preferably used as the oxidant supplied to the polymer electrolyte fuel cell, and the oxygen concentration supplied to the cathode is not particularly limited. When the gas is supplied, nitrogen or water vapor may be mixed in the oxidizer. Further, it is preferable to use air as the gas to be supplied to the cathode because a tank for storing the oxygen gas and a system for supplying the oxygen gas are not required. When the fuel and the oxidant are supplied as gases, these gases may be atmospheric pressure gas or pressurized gas.

  The gas diffusion layer of the present invention contains powder of a material having an oxygen storage/release capacity at 0 to 100°C. Presumably, the oxygen storage/release capacity is exerted as a function of oxygen propagation from the separator side to the catalyst layer, and is presumed to improve the battery characteristics. Therefore, it is possible to operate using air as the oxidant even if the amount of catalyst is reduced. Further, it is preferable that the operating temperature is set to the oxygen storage/release temperature of the material having the oxygen storage/release capacity because the power generation efficiency of the fuel cell can be increased.

  The gas diffusion electrode of the present invention preferably contains inorganic metal compound particles. Since the portion made of an inorganic metal compound has high hydrophilicity, it is easy to retain water during fuel cell operation. Therefore, when operating the fuel cell using the gas diffusion electrode of the present invention, it is possible to operate with low humidification or no humidification, further, a system without using a gas humidifier, the humidity during fuel cell operation It is possible to simplify the adjustment of.

<Specific examples of articles provided with the fuel cell>
Specific examples of articles that can include the fuel cell are not particularly limited as long as they use electricity, and include buildings, houses, tents and other structures, fluorescent lights, LEDs, organic EL, street lights, indoors, etc. Lighting, lighting equipment such as traffic lights, machinery, automobile equipment including vehicles themselves, home appliances, agricultural equipment, electronic equipment, portable information terminals such as mobile phones, beauty equipment, portable tools, sanitary goods such as toiletries Equipment, furniture, toys, decorations, bulletin boards, coolers, outdoor equipment such as generators, teaching materials, artificial flowers, objects, power supplies for cardiac pacemakers, heating and cooling power supplies with Peltier elements. In order to use electricity stably, it is preferable that the fuel cell is a system combined with a secondary battery or a capacitor.

  Hereinafter, the present invention will be described more specifically with reference to Examples. It should be noted that these are merely examples for explanation, and the present invention is not limited thereto.

(Example 1)
Cerium (III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 1.384 g and zirconyl nitrate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 0.213 g were dissolved in 500 mL of a nitric acid aqueous solution having a pH of 2.0. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5. Then, stirring was continued for 12 hours.

  After stirring was stopped and the mixture was allowed to stand, the supernatant was removed, and concentrated hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 2. A solution prepared by dissolving 0.225 g of tin(II) chloride dihydrate (manufactured by Wako Pure Chemical Industries) in 0.225 g of concentrated hydrochloric acid was added thereto. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5. Then, stirring was continued for 12 hours.

  The stirring was stopped and vacuum filtration was performed. Then, the filtration residue was repeatedly washed with water until the pH of the filtrate became 7. The obtained filtration residue was dried under reduced pressure at 80° C. and then finely pulverized in a mortar to obtain a powder.

  This powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain tin-containing ceria-zirconia powder “also referred to as material (1)”. Each evaluation described later was performed using the material (1).

(Example 2)
In the same manner as in Example 1, tin-containing ceria-zirconia precursor powder was obtained. This powder was placed in a tubular furnace and fired in a mixed gas atmosphere of hydrogen and nitrogen containing 4% by volume of hydrogen. Regarding the treatment conditions, the inside of the furnace was heated to 600° C. at a temperature rising rate of 10° C./min, held at 600° C. for 2 hours, and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain tin-containing ceria-zirconia powder “also referred to as material (2)”. Each evaluation described below was performed using the material (2).

(Example 3)
In the same manner as in Example 1, tin-containing ceria zirconia powder was obtained. 0.5 g of cobalt nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 50 mL of pure water. To this aqueous solution, 2.5 g of the tin-containing ceria zirconia powder was added and dispersed with an ultrasonic cleaner.

  While the dispersion was heated to 80° C. by an evaporator, water was slowly distilled off. The obtained solid residue was finely crushed in a mortar. Then, this powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours, and cooled to room temperature. The obtained powder was taken out and finely ground in a mortar to obtain tricobalt tetraoxide-supported tin-containing ceria-zirconia powder “also referred to as material (3)”. Each evaluation described below was performed using the material (3).

(Example 4)
In the same manner as in Example 1, tin-containing ceria zirconia powder was obtained. 2.5 g of the tin-containing ceria-zirconia powder was added to 90 ml of pure water and dispersed with an ultrasonic cleaner. To this dispersion, 0.06 g of dinitrodiammine platinum nitric acid solution (manufactured by Tanaka Kikinzoku) having a platinum concentration of 4.5% by mass and 0.75 mL of ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) were added. This solution was put into a flask and kept at 95° C. for 7 hours while stirring and refluxing under a nitrogen stream. The stirring was stopped and the mixture was filtered under reduced pressure. The obtained filtered product was dried under reduced pressure at 80° C. and then finely pulverized in a mortar to obtain platinum-supported tin-containing ceria-zirconia powder “also referred to as material (4)”. Each evaluation described below was performed using the material (4).

(Example 5)
To 250 ml of pure water, 4.2 g of activated alumina AA101 (made by Nippon Light Metal Co., Ltd.) was added and dispersed by a homogenizer, and 15 mL of 28% ammonia water was added. A solution prepared by dissolving 1.384 g of cerium (III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.213 g of zirconyl nitrate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in 100 mL of pure water was added to the dispersion. It was added dropwise with stirring at room temperature. Then, after continuing stirring for 12 hours, concentrated hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 2. To this, a solution prepared by dissolving 0.225 g of tin(II) chloride dihydrate (manufactured by Wako Pure Chemical Industries) in 0.225 g of concentrated hydrochloric acid was added. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5.

  Then, the mixture was stirred for 12 hours and then filtered under reduced pressure. The filtration residue was washed with water repeatedly until the pH of the filtrate became 7. The obtained filtration residue was dried under reduced pressure at 80° C. and then finely pulverized in a mortar to obtain a powder. This powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours, and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain an alumina carrier tin-containing ceria zirconia powder “also referred to as material (5)”. Each evaluation described later was performed using the material (5).

(Example 6)
In the same manner as in Example 5 except that titanium oxide F6 (manufactured by Showa Denko) was used instead of activated alumina AA101 (manufactured by Nippon Light Metal Co., Ltd.), titania carrier tin-containing ceria zirconia powder "also referred to as material (6)". Got Each evaluation described below was performed using the material (6).

(Example 7)
In the same manner as in Example 5, an alumina carrier tin-containing ceria zirconia powder was obtained. To a solution prepared by dissolving 0.5 g of cobalt nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in 50 mL of pure water, 2.5 g of tin-containing ceria-zirconia powder containing alumina carrier was added and dispersed using an ultrasonic cleaner. .. While the dispersion was heated to 80° C. by an evaporator, water was slowly distilled off. The obtained solid residue was finely crushed in a mortar. Then, this powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours, and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain an alumina carrier tricobalt tetraoxide-supported tin-containing ceria-zirconia powder “also referred to as material (7)”. Each evaluation described below was performed using the material (7).

(Example 8)
Cerium (III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 1.384 g and zirconyl nitrate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 0.213 g were dissolved in 500 mL of a nitric acid aqueous solution having a pH of 2.0. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5. Then, stirring was continued for 12 hours.

  After stirring was stopped and the mixture was allowed to stand, the supernatant was removed, and concentrated hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 2. A solution prepared by dissolving 0.341 g of bismuth nitrate pentahydrate (manufactured by Wako Pure Chemical Industries) in 0.341 g of concentrated nitric acid was added thereto. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5. Then, stirring was continued for 12 hours.

  The stirring was stopped and vacuum filtration was performed. Then, the filtration residue was repeatedly washed with water until the pH of the filtrate became 7. The obtained filtration residue was dried under reduced pressure at 80° C. and then finely pulverized in a mortar to obtain a powder.

  This powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours, and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain a bismuth-containing ceria-zirconia powder “also referred to as material (8)”. Each evaluation described later was performed using the material (8).

(Comparative Example 1)
Cerium (III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 1.384 g and zirconyl nitrate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 0.213 g were dissolved in 500 mL of a nitric acid aqueous solution having a pH of 2.0. While stirring at room temperature, 28% ammonia water (manufactured by Wako Pure Chemical Industries) diluted 5 times with pure water was added dropwise to adjust the pH to 10.5.
Then, the mixture was stirred for 12 hours and filtered under reduced pressure. The filtration residue was repeatedly washed with water until the pH of the filtrate became 7. The obtained filtration residue was dried under reduced pressure at 80° C. and then finely pulverized in a mortar to obtain a powder. This powder was fired in the atmosphere in a muffle furnace. Regarding the treatment conditions, the inside of the furnace was heated up to 400° C. at a temperature rising rate of 10° C./min, then held at 400° C. for 6 hours, and cooled to room temperature. The obtained powder was taken out and finely pulverized in a mortar to obtain a ceria-zirconia powder “also referred to as material (9)”. Each evaluation described below was performed using the material (9).

(Comparative example 2)
Baking treatment conditions in the atmosphere were the same as in Example 1 except that the temperature inside the furnace was raised to 800° C. at a temperature rising rate of 10° C./min, the temperature was held at 800° C. for 2 hours, and the temperature was cooled to room temperature. , Tin-containing ceria-zirconia powder “also referred to as material (10)” was obtained. Each evaluation described below was performed using the material (10).

<Powder X-ray diffraction>
The powder X-ray diffraction analysis of the sample was performed using X'Pert PRO MRD manufactured by PANalytical.
The measurement was performed under the following conditions.
X-ray output (Cu-Kα): 45kV, 40mA
Scanning axis: θ/2θ
Measuring range (2θ): 10.00° to 89.98°
The powder X-ray diffraction (XRD) pattern of the material (1) using Cu-Kα as the X-ray light source is shown in FIG. The powder X-ray diffraction (XRD) pattern of material (9) is shown in FIG. The powder X-ray diffraction (XRD) pattern of material (10) is shown in FIG.

  The pattern of FIG. 1 is shifted to a higher angle side than the pattern of FIG. The material (1) was identified as an oxide in which cerium, zirconium, and tin were solid-solved, and the material (9) was identified as an oxide in which cerium and zirconium were solid-solved. In the pattern of FIG. 3, a peak different from the pattern of FIG. 1 was observed, and it was identified as tin oxide that did not form a solid solution.

<BET specific surface area measurement>
0.15 g of a sample was sampled, and the specific surface area was measured with a full-automatic BET specific surface area measuring device Macsorb (manufactured by Mountech Co., Ltd.). The pretreatment time and pretreatment temperature were set to 30 minutes and 200° C., respectively.
Table 1 shows the specific surface areas calculated by the BET method obtained from the TPRs of the materials (1) to (10). The specific surface areas of materials (1) to (9) calculated by the BET method were all 70 m ² /g or more. The specific surface area of the material (10) calculated by the BET method was smaller than 70 m ² /g.

<Hydrogen-Temperature Reduction (TPR)>
H2-TPR was measured by a catalyst analyzer BEL-CAT (manufactured by Nippon Bell). As a pretreatment, the sample was kept at room temperature for 10 minutes while flowing helium gas, then the gas was switched to oxygen, the temperature was raised to 200° C. at a temperature rising rate of 10° C./min, and the sample was kept for 30 minutes and cooled to 0° C. did. As a measurement, after switching the gas to argon and holding it for 10 minutes, switching the gas to a mixed gas of hydrogen and argon nitrogen containing 5% by volume of hydrogen, raising the temperature to 500° C. at a heating rate of 5° C./minute, and holding it for 30 minutes. did. The hydrogen consumed during this period was continuously measured by a quadrupole mass spectrometer (MS) and a thermal conductivity detector (TCD).

  Table 1 shows the oxygen release initiation temperatures obtained from the TPRs of the materials (1) to (10). The oxygen release start temperature of materials (1) to (8) is in the range of 0 to 100°C, and the oxygen release start temperature of materials (9) to (10) is higher than 100°C.

<Ionization potential>
The ionization potential was measured using a photoelectron spectrometer MODEL AC-2 manufactured by Riken Keiki Co., Ltd.
The materials (1) to (10) were spread with a spatula on the UV irradiation portion of the sample table of the measuring device, and the measurement was performed. Under the following measurement conditions, the excitation energy of ultraviolet rays was scanned from 4.5 to 5.7 eV from the lower side to the higher side.
Set light intensity: 500nW
Counting time: 15 seconds Scan interval: 0.1 eV

  The photoelectrons emitted at this time were measured, and a graph was created with the normalized photoelectron yield (Yield^n) on the vertical axis and the excitation energy (eV) on the horizontal axis. Here, the normalized photoelectron yield (Yield^n) means the n-th power of the photoelectron yield per unit amount of light. The value of n was 0.5. The excitation energy until the electron emission started and the excitation energy after the electron emission started were designated by the measuring device. From the graph, a threshold value at which photoelectron emission starts was calculated, and the threshold value was used as an ionization potential.

Table 1 shows the ionization potentials obtained from the TPRs of the materials (1) to (10).
Material (2) and material (3) have lower ionization potentials than materials (1) and materials (4) to (10).

[Gas diffusion layer with microporous layer and its evaluation]
<Production of ink for forming microporous layer>
In a small mixer, 0.15 g of Ketjen Black ECP600JD (manufactured by Lion Corporation) and 0.45 g of VGCF (manufactured by Showa Denko KK) were mixed, and then mortar was crushed in advance to obtain scaly graphite FBF (Chuetsu Graphite Mill ( 1.2 g) (manufactured by Co., Ltd.) was added and mixed, and further 1.2 g of the material (1) was added and mixed. 1.4 g of this mixture, 3.6 g of a mixture consisting of 8 parts by mass of the dispersant Triton X-100 (manufactured by Wako Pure Chemical Industries, Ltd.) and 2 parts by mass of solvent Solfit (manufactured by Kyowa Kako Co., Ltd.), and a fluorine-based compound. 1 g of a resin (aqueous solution containing NAFION (registered trademark) (5% NAFION (registered trademark) aqueous solution, manufactured by Wako Pure Chemical Industries, Ltd.)) was mixed. Further, a proper amount of a mixture of 8 parts by mass of Triton X-100 and 2 parts by mass of Solfit was added so as to have a viscosity suitable for coating, and the ink for forming a microporous layer (1) "coating liquid ( Also referred to as 1)."

  Using the materials (2) to (10), coating solutions (2) to (10) were prepared in the same manner as above.

<Production of gas diffusion layer with microporous layer>
Next, using an automatic coating device PI-1210 (manufactured by Tester Sangyo) on the surface of carbon paper GP-H-H-060 (manufactured by Chemix Co., Ltd.) that has been previously made water repellent, a coating liquid is applied with an applicator. (1) was applied. After drying at room temperature, it was heated at 360° C. for 30 minutes to obtain a gas diffusion electrode (1) with a microporous layer (hereinafter sometimes referred to as “gas diffusion layer”). The basis weight of the gas diffusion electrode with the microporous layer was adjusted so that the Gurley number of the GDL with the MPL film was 20 sec±5 sec/100 ml. Using the coating liquid (2) to the coating liquid (10), in the same manner as above, the gas diffusion layer (2) with a microporous layer (also referred to as "gas diffusion layer (2)") to the gas with a microporous layer. Diffusion layer (10) A "gas diffusion layer (10)" was produced.

<Measurement of basis weight of microporous layer>
The basis weight (mg/cm ² ) of the microporous layer of the gas diffusion layer (1) is obtained by dividing the difference between the mass of the gas diffusion layer (1) and the mass of the gas diffusion electrode substrate by the area per unit area. I asked.

Similarly to the above, the basis weights of the microporous layers of the gas diffusion layer (2) to the gas diffusion layer (10) were measured. Table 2 shows the measured areal weight of the microporous layer. The basis weight of the microporous layers of the gas diffusion layer (1) to the gas diffusion layer (10) was 1.5 to 5 mg/cm ² .

<Measurement of Gurley>
The Gurley (second) of the gas diffusion layer (1) was measured using a No323-AUTO automatic Gurley type densometer (manufactured by Yasuda Seiki Seisakusho).

  Gurley of each of the gas diffusion layer (2) to the gas diffusion layer (10) was measured in the same manner as above. Table 2 shows the measured Gurley numbers. The Gurley number of the gas diffusion layer (1) to the gas diffusion layer (10) was 15 to 25 seconds.

<Measurement of conductivity>
The resistance value (Ω) of the gas diffusion layer (1) was measured by LORESTER GP MCP-T610 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the obtained resistance value was converted into conductivity (S/cm).

  In the same manner as above, the conductivity of each of the gas diffusion layer (2) to the gas diffusion layer (10) was measured. The measured conductivity is shown in Table 2. The conductivity of the gas diffusion layer (1) to the gas diffusion layer (10) was 80 S/cm or more.

[Manufacture of membrane electrode assembly for fuel cell and evaluation of its power generation characteristics]
<Production of ink for forming air electrode catalyst layer>
An aqueous solution containing a fuel cell catalyst Pt/C (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo TEC10E50E) 90.0 mg and a polymer electrolyte (Nafion (NAFION (registered trademark)) (5% NAFION (registered trademark) aqueous solution, Wako Pure) 0.75 g, manufactured by Yakuhin Co., Ltd., 3.75 mL of pure water, and 3.75 mL of isopropanol (manufactured by Junsei Kagaku) were added. The liquid was subjected to ultrasonic treatment for 30 minutes in ice water to produce an ink for forming an air electrode catalyst layer.

<Production of gas diffusion layer with air electrode catalyst layer>
On the surface of the microporous layer of the gas diffusion layer (1), an air electrode catalyst layer forming ink was applied at 80° C. by an automatic spray coating device (manufactured by San-Ai Tech Co., Ltd.), and gas diffusion with an air electrode catalyst layer was performed. Layer (1) was produced. The basis weight of the catalyst layer of the gas diffusion layer with the air electrode catalyst layer was 0.1 mg/cm ² .

  Using the gas diffusion layer (2) to the gas diffusion layer (10), the gas diffusion layer with the air electrode catalyst layer (2) to the gas diffusion layer with the air electrode catalyst layer (10) were manufactured in the same manner as above.

<Production of ink for forming fuel electrode catalyst layer>
An aqueous solution (5% Nafion (registered trademark)) containing 0.6 g of a platinum-supported carbon catalyst for fuel cells (TEC10E70TPM manufactured by Tanaka Kikinzoku Kogyo) and a polymer electrolyte (NAFION (registered trademark)) in 50 ml of pure water. ) Aqueous solution, manufactured by Wako Pure Chemical Industries, Ltd.)) and 5 g were prepared. The liquid was subjected to ultrasonic treatment for 60 minutes to prepare an ink for forming a fuel electrode catalyst layer.

<Manufacture of gas diffusion layer with fuel electrode air electrode catalyst layer>
Carbon paper TGP-H-060 (manufactured by Toray Industries, Inc.) was immersed in acetone (manufactured by Wako Pure Chemical Industries, Ltd.) for 30 seconds to degrease it, then dried, and then 10% by mass of polytetrafluoroethylene (PTFE). ) Immersed in the aqueous solution for 30 seconds. Then, it was dried at room temperature and further heated in the air at 350° C. for 1 hour to obtain a water-repellent anode gas diffusion electrode in which PTFE was dispersed in the carbon paper. On one surface of the fuel electrode gas diffusion layer, an ink for forming a fuel electrode catalyst layer was applied at 80° C. by an automatic spray coating device (manufactured by Sanei Tech Co., Ltd.) to produce a gas diffusion layer with a fuel electrode catalyst layer. .. The basis weight of the catalyst layer of the gas diffusion layer with the fuel electrode catalyst layer was 1.0 mg/cm ² .

<Production of membrane electrode assembly>
A Nafion (NAFION (registered trademark)) film (NR-212, manufactured by DuPont) was prepared as a solid polymer film. The respective catalyst layers of the gas diffusion electrode with the catalyst layer for the anode and the gas diffusion layer (1) with the air electrode catalyst layer were arranged such that the catalyst layer surfaces face each other with the solid polymer membrane sandwiched therebetween. Using a hot press machine, these were thermocompression-bonded at a temperature of 140° C. and a pressure of 1 MPa for 7 minutes to prepare a membrane electrode assembly (1).

  Using the gas diffusion layer with an air electrode catalyst layer (2) to the gas diffusion layer with an air electrode catalyst layer (10), a membrane electrode assembly (2) to a membrane electrode assembly (10) are produced respectively in the same manner as above. did.

<Preparation of polymer electrolyte fuel cell>
The membrane electrode assembly (1) is sandwiched between two sealing materials (gaskets), two separators with gas passages, two current collectors and two rubber heaters, and then fixed with bolts and tightened to obtain a single cell solid height. A molecular fuel cell (1) (hereinafter also referred to as “fuel cell (1)”) (cell area: 25 cm ² ) was produced.

  Using the membrane electrode assembly (2) to the membrane electrode assembly (10), the fuel cell (2) to the fuel cell (10) were manufactured in the same manner as above.

<Evaluation of power generation characteristics>
In the fuel cell (1), the cell temperature was adjusted to 80° C., the humidity of the anode was adjusted to dew point 77° C., and the cathode was not humidified. Hydrogen gas was supplied to the anode side as a fuel so that the utilization rate would be 70%. Air was supplied to the cathode side so that the utilization rate was 40%. The current-voltage (IV) characteristic of the fuel cell (1) was evaluated.

In the same manner as above, the current-voltage (IV) characteristics of the fuel cell (2) to the fuel cell (10) were evaluated. The current density (mA/cm ² ) at 0.7 V is shown in Table 3.

Claims (10)

Containing carbon material, water repellent material, a material having a oxygen storage and release capacity,
The material having the ability to store and release oxygen is
Has an oxygen release initiation temperature of 0 to 100° C., and
Cerium zirconium oxide containing at least one element selected from tin, manganese, praseodymium and bismuth
Microporous layer for fuel cells . The material having the oxygen storage/release capacity is supported on a substrate, and the substrate is one or a mixture of two or more selected from alumina, silica, silica-alumina, titania, zeolite, zirconia and magnesia. microporous layer for a fuel cell according to 1. The oxygen storage material having a releasing capacity for a fuel cell microporous layer according to any one of claims 1 to 2 carrying a transition metal element. The carbon material, fuel cell microporous layer according to any one of claims 1 to 3 carbon particles or carbon fibers. The water-repellent material, fuel cell microporous layer according to any one of claims 1 to 4, which is a fluororesin. Fuel cell microporous layer and the gas diffusion electrode base material and the gas diffusion layer are laminated according to claim 1-5. An air electrode catalyst layer and a fuel electrode catalyst layer arranged via a solid polymer membrane,
Was further disposed on the outside of the air electrode catalyst layer, and the cathode gas diffusion layer having a fuel microporous layer battery according to any one of claims 1 to 5
A membrane electrode assembly having a fuel electrode gas diffusion layer disposed outside a fuel electrode catalyst layer. An air electrode catalyst layer and a fuel electrode catalyst layer arranged via a solid polymer membrane,
Was further disposed on the outside of the air electrode catalyst layer, and the cathode gas diffusion layer is a gas diffusion layer according to claim 6,
A membrane electrode assembly having a fuel electrode gas diffusion layer disposed outside a fuel electrode catalyst layer. A fuel cell comprising the membrane electrode assembly according to claim 8. The operating method of the fuel cell according to claim 9 , wherein the temperature of the microporous layer in the fuel cell is set to be equal to or higher than the oxygen release start temperature of the material having the oxygen storage/release capacity.